When accesses occur from a plurality of transactions to a database at the same time, data consistency in the database is guaranteed by performing exclusive control. At this time, until one of conflicting transactions has committed or rolled back data update, the other of the transactions is placed in a waiting state. That is to say, in exclusive control, it is not possible to execute a plurality of transactions in parallel, and thus the processing efficiency of transactions deteriorates. On the other hand, techniques for executing conflicting transactions in parallel are known (for example, refer to Japanese Laid-open Patent Publication No. 11-85544 and Japanese Laid-open Patent Publication No. 2012-155498).
Also, in update processing of a database, Multi-Version Concurrency Control (MVCC) is known as a technique for executing online processing and batch processing in parallel. In MVCC, while a record before an update is stored in the database, a record after the update is added in the database as a new record so that a plurality of new version records and old version records are managed. Thereby, it is possible to perform online processing that updates a relatively small amount of records and batch processing that updates a relatively large amount of records in parallel.